What is a dolphin kick?
As you’ll see if you watch someone swimming butterfly, it’s a kick where the legs are extended straight back and move up and down in unison, with a slight bend in the knees on the upward movement. According to World Aquatic rules, all up and down movements of the legs must be simultaneous. The legs or the feet need not be on the same level, but they can’t alternate in relation to each other.
Think of it like a bow and arrow. When you’re on your stomach, the ‘up kick’ is when the arrow is being pulled back and the ‘down kick’ is when the arrow is released. Both actions are needed to get the arrow to fly a long distance and at high speed. It’s the feet that create the propulsion, the rest of the process simply increases how much propulsion can be generated by the feet with each kick.
A dolphin kick can produce speeds up to 25% faster than a freestyle kick. This is because both legs come down and hit the water with a larger surface area. You get some help from the vortex of the waves produced by the downward motion, and you’re recruiting/using more muscles during this kick.
Even though a dolphin kick is similar to freestyle in that the down-kick generates most of the propulsion, you also get more help from your up-kick with two legs versus one.
How to learn the dolphin kick
Begin with leg lifts on land. Start with 3×10 leg lifts and maybe 3×30-second leg holds at the top of the lift to work your core strength. For a successful dolphin kick, the swimmer must be strong!
From there, it’s time to get into the pool. The dolphin kick starts from the core/back and is translated through the hips, legs, knees, ankles and feet. That’s why most coaches describe the dolphin kick as a wave. You create a continuous undulation, which starts at the midsection and moves down to the feet.
Begin by floating in the water with your face and chest down, legs close together, arms and feet extended but with your ankles relaxed. To start the upper body undulation, press the chest down, then release it. As you release the chest, push down on the hips, and vice versa.
As you push the hips down, the upper legs follow and knees bend. Now as the hips move up, the thighs follow and you extend the knees and feet to perform the kick, snapping down the lower legs.
Next, try a drill using a board and snorkel to help you learn the flow and toe point required with the dolphin kick. Grab and hold onto the base of the kickboard while pushing the head through the arms towards the bottom of the pool.
The key when using the snorkel is to keep the body in alignment and focus on making sure that you’re kicking down past your horizontal line, so the kick happens in front of the body as opposed to in line with the body. This utilises the quads, the biggest muscles in the legs, and generates more power.
Keeping the head down through the arms also works on the chest press and makes the kick more efficient.
Try 8×25s like this. Then, try going underwater for a few dolphin kicks to start working your anaerobic capacity. From there, start swimming a lap and try a few repeats of that. Maybe 4x50s to start. Remember to focus on moving water in both directions.
Tips for improving your dolphin kick
A great dolphin kick requires good timing, technique, mobility and anaerobic capacity. You need:
- Core strength to sustain moving the legs up and down together.
- An anaerobic engine to be comfortable in an oxygen debt situation.
- Pointed toes or great plantar flexion to really move some water with your feet. Remember: it is only the feet that push a swimmer forward in the pool. Try not to kick from your knees, hips, back or core. They are all a necessary part of the wave, but you only move forward with help from your feet!
- To practise, practise, practise the fluidity of your dolphin kick, so you create that nice flow and wave-like motion.
You can read more articles about swimming techniques in issue 7 of Swim magazine.